Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kerne…

…l/git/paulmck/linux-rcu

Pull fix for hlist_entry_safe() regression from Paul McKenney:
 "This contains a single commit that fixes a regression in
  hlist_entry_safe().  This macro references its argument twice, which
  can cause NULL-pointer errors.  This commit applies a gcc statement
  expression, creating a temporary variable to avoid the double
  reference.  This has been posted to LKML at

    https://lkml.org/lkml/2013/3/9/75.

  Kudos to CAI Qian, whose testing uncovered this, to Eric Dumazet, who
  spotted root cause, and to Li Zefan, who tested this commit."

* 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  list: Fix double fetch of pointer in hlist_entry_safe()

include/linux/list.h

@@ -667,7 +667,9 @@ static inline void hlist_move_list(struct hlist_head *old,
 	     pos = n)
 
 #define hlist_entry_safe(ptr, type, member) \
-	(ptr) ? hlist_entry(ptr, type, member) : NULL
+	({ typeof(ptr) ____ptr = (ptr); \
+	   ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
+	})
 
 /**
  * hlist_for_each_entry	- iterate over list of given type